Ball mill



Jail '21, 1930. F. o. WILLIAMSON 1,744,089

BALL MILL Filed May 21, r1928 m 5, m, 41,9 TLSQ- 50 QD) OJ) D f EMDQGDQ E Cao o o o@ QD 5%? C C \C lNvf-:NTOR

b f F p Y Ik ffm/mr 0, W//z/A/ffo/v. w() Bo E @3Q 2D@ @ga Jil. ODo a 41.11

BY E

ATPORNEYS Patented Jan. 21, 1930 PATENT OFFICE FRANCIS O. WILLIAMSON, F ALAMEDA, CALIFORNIA BALL MILL Application led May 21, 1928.

This invention relates to ball or pebble mills of the type shown in my prior Patent No. 1,413,644 of April 25, 1922, and has for its objects the provision of improved deflecting heads for the mill whereby a more efficient ball movement is obtained, and consequently a superior ground product is produced by the mill in a given length of time or with a given expenditure of horsepower. Aln so such a deflecting head which is better adapted to compartment mills of the ball type.

Briefly described the invention comprisesl a cylindrical revolvable mill with deflecting vanes or wedges arranged within on the confronting heads of the mill, similar to those shown in my patent aforesaid with the exception that all, or substantially all elements of the vanes or wedges slant from the periphery of the mill in a direction toward the axis of the cylinder but away from the head t0 which they are attached or form a part, Or more correctly no part of the wedge shaped developments slant in the reverse direction from that explained above or as shown in my prior patent aforesaid in Figs. 1 and 2 at 9 and 10.

Besides the above it is desirable that all the wedge elements as above first defined shall extend tangentially to a circle around the main axis of the mill or to a cone or cylindrical development therearound, or other figure concentric with the axis.

Further when the defiecting heads are used in cylindrical chambers to form compartment mills, a spaced pair is used to form a material receiving chamber between each two compartments, and certain faces of the'wedges are left open in a manner so that material can flow into successive compartments yet preventing the balls from doing so, on account of the direction of rotation of the mill.

In the drawings accompanying this application Fig. 1 is a vertical and longitudinal section through a typical portion of a conpartment ball mill constructed 1n accordance Serial No. 279,366.

with my invention, having four deilecting wedges on each head.

Fig. 2 is an isometrical view of the righthand end of a mill showing siX deflecting wedges in position.

Figs. 3, 4, 5, G and 7 are reduced size diagrannnatic front views of different heads showing various modifications to the tangentially arranged deflecting wedges on the inner surface of the heads.

Figs. 8, 9, 10 and 11 are views showing cross-sections of variously formed deflecting wedges optionally used on the heads.

In further detail the drawings show a mill comprising a cylindrical shell 1 provided with tubular bearing trunnions 2 at opposite ends (one only being shown) supported in self aligning bearings 3 of conventional con struction.

Within the cylinder are suitable liner or wearing plates 4 bolted or otherwise held in place and which liner plates are made in relatively small sections so as to be replaceable through a suitable man-hole (not shown) in the cylinder.

The cylindrical shell may be of any diameter or length depending on the requirements of the particular mill, though usually it will be of a length about equal to its diameter if of the single chamber variety, or `multiples thereof for the compartment mills.

In the construction shown in Fig. l the trunnion bearings 2 are formed integral with the outer head 5 of the cylinder and also with a relatively short piece 6 of the cylindrical shell itself, being joined at 7 by means of bolt flanges to the main body of the shell.

Within the short cylindrical portion 6 of the outer head is positioned one of my improved deflecting heads 8.

This deflecting head 8 is bored about the saine internal diameter as the trunnion bearing 2 and a feed tub 9 extends through both members as shown in Fig. 1. The feed tube is preferably of smaller diameter at its outer end so as to provide a slightly downward ineline at its bottom so that material will readily eed therethrough with the mill mounted on a level axis of rotation.

Spaced from the inner head 8 ant secured in place by any suitable means such as the bolts indicated are two dctiecting heads 1,0, 11 arranged to provide a relatively large hollow space 12 between them, and these heads are also provided with central bores 13-14.

Beyond the spaced heads 10, 11 may be a number of similar heads, followed by a head at the other end of the cylinder so to provide any number of compartments, or for a single compartment mill but two complementary end heads of the kind shown at S are used.

As stated, the heads are provided with wedgesliaped deflecting surfaces simiiar to those shown in my prior patent aforesaid with the exception of the development of the planes involved.

There may be any number of wedge elements arranged on the heads, four being used in Figs. 1 and 3 to 7, and six in Fig. 2.

The wedge elements in the present case each have a long apex A extending from adjacent the inner` periphery of the shell to a point of tangency with a circle 'B concentric with the axis of the mill and at a slight angle in a direction extending toward the opposite end of the mill, or toward the confronting head 1() if in a compartment mill. In the tormer patent the angle of the apices of the wedges was from the periphery of the mill back toward the head or toward the niill axis but away from the opposite or confronting head, thus diifering from the presentshowing.

The apices A of the wedges in 1, 2, 6 and 7 are shown as straight lilies. whereas in Fig. 3 as convex curves tangential to the circle B, in Fig. 4 concave, and in Fig. 5 as an OG curve.

The plane or ball detlecting surface C ofthe 'wedge elements may be arched, OG, or straight as shown respectively in Figs. S to 10, and the termination of the wedge element or base thereof may be substantially at right angles with the plane of the head shown at D in Figs. 1, 2. 8 and 9 or it may be less abrupt as Shown at E in Fig. 10, or concavely curved as shown at F in Fig. 11, and in any of the modifications the base joins the next wedge plane C on a base line G also extending from the periphery of the head toward t 11C axis of the mill and toward the opposite end or confronting head of the mill, while terminating tangentially with respect to circle B.

It has been found after exhaustive experiments that a ball mill provided with confronting detlecting heads compliniientarily formed along the principles of design above explained and revolved in direction of the arrows of Figs. 1 and 2 will effect great economy in time of grinding as well as overcome the excessive wear on the deilecting surfaces found with thc old style heacs. This is thought due to the combination of angular and tangential development of the surfaces C which results in a constant falling away of these suriaces behind the mass of balls being lifted in rotation of the mill, combined with the greater percussive action of the balls upon leaving the said surfaces.

Vhile I show in Fig. 2 the inner ends of both lines A and G meeting at the same point against the circle B, this may be varied 'within reasonable limits by decreasing the angle of line G at the hub of the head and then more or less abruptly curving out to meet line A.

In the showing of Fig. 1 intermediate head 10 is provided on the surface of the dei'lectors with small pertorations in the form of slits 15 for the passage of ground material to the space 12 between the intermediate heads 10 and 11 and from which space the ground material automatically discharges to the next compartment of the mill to the left of head 11 upon rotation of the mill for further grinding by balls or pebbles therein, and thence to still another compartment if desired, or to iinaliy d therefrom, if the latter be the last t l nient.

The discharge of the ground material from the intermediate head space 12 is effected through openings in the D Walls of the liead, or omission of said walls in head 11. These openings are hard to understand in Fig. 1 though they are indicated at 1G, and to further clarify the construction a dotted line 16, is drawn on the isometrical view Fig. 2 of head 8 as it is similar in other respects to head 11.

It should be understood that I show the detlecting head 8 as a separate part 'for ease of manufacture and replacement, butif desired the wedge elements may be cast directly on the main cylinder head 5.

It should also be understood that. while I show the inner ends of the wedge elements extending tangent to a circle B, they may be tangent to any other figure arranged around the main axis of the mill.

In operation the mill compartment or compartments are charged with various size grinding balls or pebbles and material to be ground substantially to the dotted line 17. the mass banking up towards the center of each compartment as indicated at 17 owing to the action of the deflecting surfaces C. In intermediate space 12 the ground material 1S received through slits .15, due to the interior surfaces of the deflecting wedges and direction of rotation of the mill, is continually discharged to the following compartment, and at the same time any of the grinding balls from the second compartment which may back up into space 12 will roll out.

The peculiar arrangement of the angular deecting surfaces herein shown, for the reasons already stated, has been found to result in a much longer life to the wedge elements besides giving the grinding balls a combination of rolling or grinding action followed by a better impact action toward the center of the mill than possible to obtain in the earlier construction.

While I show the deflecting heads as made of one piece castings, this is for simplification of the drawing only, as it is manifest they may be made in any number of parts bolted to the members 5 and 6. Also it should be noted that the special form of end or outer head members 5 including a deep ring 6 parted from the main shell I at 7 constitutes new construction providing for removal of the body of the mill by slight axial separation of the end bearings 3.

It is of course understood without showing in the drawings that any form of gear or other drive for the mill is to be incorporated in the construction.

I claim:

l. In a mill of the character described7 a revolvable shell, heads on said shell, deflects arranged.

2. In a mill of the character described, a revolvable shell, heads on said shell, defiecting wedges arranged on the confronting faces of said heads, said wedges including a series of main surfaces extending from the periphery of the head generally towards the axis of the mill and towards the confronting head.

3. In a mill of the character described, a cylindrical shell, heads on said shell, means by which said shell is mounted for revolution on a horizontal axis extending longitudinally of the cylinder, a series of wedge-shaped defleeting` elements within the shell arranged against the heads in confronting relation, said elements provided with working surfaces extending generally towards the axis of the mill and towards the confronting series of deflecting elements.

1l. In a mill of the character described, a cylindrical shell, heads on said shell, and an intermediate head forming compartments in said shell, said intermediate head provided with an interior space and a series of similar wedge-shaped deflecting elements on opposite outer sides formed with openings whereby ground material will pass from one compartment of the mill to the other.

5. In a mill of the character described, a cylindrical shell, heads on said shell, said heads formed with a cylindrical return shell FRANCIS O. WILLIAMSON. 

